Portable stair



FIG. 1 is a front elevation of the portable stair of the present invention, the rear side elevation being the mirror image of the front elevation;

FIG. 2 is a right side elevation of the portable stair of FIG. 1, the left side elevation being the mirror image of the right side elevation;

FIG. 3 is a top plan view of the portable stair of FIG. 1; and,

FIG. 4 is a bottom plan view of the portable stair of FIG. 1. 

The ornamental design for a portable stair, as shown. 